I'm assuming most are aware of below but its probably worth mentioning.

Just because you generate say 25kw in a day does not mean your power bill will be neutral even if you use only 20kw a day.  It all depends on the distribution of usage through the day.  If you use the bulk of power at night then the gain is going to be less whereas of you use most of your power when the system is at its peak,  your bill will be less.  Of course this all depends on what you are paid for the power you generate.  If you are paid 44c then you are better using less during the day (and be paid 44c for generated) and more at night (and paying 28c for it).

If you are being paid under 28c then you are better using generated power during the day (when it is effectively free) and minimise use at night.

  people forget this, and this is the reason solar is no longer viable to install now in Victoria as the tariffs they pay you for electricity produced is hardly anything on new system installations